Brush-holder



.(No M0de1.1 J. R. COFFMAN.

BRUSH HOLDER.

A No. 519,892. Patented Dee. 19, 1893.

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UNITED STATES PATENT OEEICE.

JOHN R. COFFMAN, OF DETROIT, MICHIGAN, ASSIGNOR OF ONE-HALF TO THE EUREKA TEMPERED COPPER COMPANY, OF NORTH EAST, PENNSYLVANIA.

BRUSH-HOLDER.

SPECIFICATION forming part of Letters Patent No. 510,892, dated December I9, 1893.

Application tiled December 9, 1892. Serial No. 454,558. (No model.)

To all whom it may concern:

Be it known that I, JOHN R. COFFMAN, a citizen of the United States, residing in the city of Detroit, in the county of lVayne and State of Michigan, have invented certain new and useful Improvements in Brush-Holders; and I do hereby declare that the following is a full, clear, and exact description of the invention, such as will enable others skilled in 1o the art to which it appertains to make and use the same.

My invention relates to improvements in brush holders for dynamo-electric machines or electric motors, the object being to provide a holder which will retain the brush in the proper position against the commutator plates with a light uniform pressure, and in which the brush may be adjusted by suitable clamps.

The invention consists in the combination zo of a support or frame, abrush carriage mounted in and adapted to reciprocate on said support, a brush mounted in said carriage, means for locking the brush in the carriage and means for impelling the carriage and holding the brush to its work.

It also consists in other arrangements and combinations of parts, as more fully hereinafter set forth and claimed.

In the drawings, Figure l, is a plan view of 5o the device embodying my invention. Fig. 2, is a vertical central section of the same. Fig. 3, is a side elevation; and Fig. 4, is a rear end elevation of the same.

A is the main frame or support, made of 3 5 copper o r other suitable conducting material,

and B is the brush carriage mounted in suitable ways d d in the frame A along which it is adapted to reciprocate. This carriage has flanges b b on each side extending longitudi- 4o nally along its upper face and merging into risers B B. These ilanges and risers form a seat for the carbon brush C.

D D are levers mounted on a rod (Z extending through the risers D D, having cam surfaces d d on their lower faces.

E is the clamp plate loosely fitted between the risers B, between which and the bottom of the carriage B, the carbon C is inserted. On the top of the clamp plate is secured a 5o pair of liat springs e e, beneath the free ends of which is a small strip of rubber or other bushing. The clamps D D bear against these springs and by a downward movement of the levers the cam or eccentric portion bears against the clamp plates and retains the carbon to its seat. The plate E is also provided with a boss E which is suitably bored or recessed for the insertion of an electric cable or conductor.

F is a coil spring, one end of which is secured to the shaft G mounted in bearings in the extended portions A A of the frame A, and the other end is secured to the rear end of the piece Il. This piece Il is formed in the shape of a segment of acircle,and is mounted loosely atits axis on the shaft G. To the other end of the segmental part H, is secured one end of a strap h, preferably made of sheet copper, the other end of said strap being secured to the rear of the carriage B. In this manner, the power of the spring is transmitted to the carriage B and tends to impel it to its forward position.

I is the ratchet-wheel secured to the inner end of the shaft G and engaged by the pawl .l on the frame A. At the other end of the shaft G is a thumb nut K by which the shaft may be turned to wind up or increase the pressure of the spring F and thereby augment the pressure of the carbon against the commutator plates, to prevent sparking. The spring is held at any desired tension by means of the pawl and ratchet I and J.

L is a clamp for locking the carriage B at any point along its range of movement. It consists merely of a cam-shaped rod passing through the frame A and having a thumb nut by which it may be turned. In turning, the eccentric portion l bears against the under face of the carriage and holds the same in its place.

In using my device, the carbon is inserted originally by raising the clamp levers D D and slipping it in its seat under the clamp plate E. The levers are then turned down and the carbon clamped in proper position with one end projecting a short distance beyond the front of the carriage. This projecting end of the carbon bears against the commutator plates and is held to its work with a slight pressure by the spring F, through the part H, strap h and carriage B. As the IOO carbon becomes worn, it is necessary to force it farther along in its seat. To do this, I draw back the carriage against the force of the spring and clamp it in its rearward position by means of the eccentric clamp L. The carbon clamps D D are then released, the carbon is pushed forward to the desired position, reclamped, the carriage unclamped, v

and the brush is ready to proceed with its work.

It has been found in practice thatas the carbon becomes worn, the spring becomes necessarilyiyveaker, and if the proper tension is not kept onfthe carbon against the commutator plates, it causes sparking at the point of contact, and thereby a burning out of both the carbon and the commutator. It has also been .found that the heat in the brushes transmitted to the springs takes the temper out of the same and thereby weakens them. Itis to overcome this objection to other devices, therefore, that I have provided the simple and eliicient means already described of increasing the tension of the spring. If at any time it becomes necessary to add to the pressure of the carbon against the commutator, one has to but give the button K a turn a distance of one or more notches on Ythe ratchet I, and the proper additional tension is obtained.

From the above description, it will be seen thatk I have devised a simple and complete devicefor the purpose sought. The carbon is constantly kept against the commutator plates bya spring pressure. Any length of carbon` maybe used and the thickness need not be so exact as in other holders. The car-v bon may be fed forward from time to time as it becomes worn, and the pressure of the spring actuating the carriage may be suitably adjusted. e

What I claim as my invention therefore, and desire to secure by Letters Patent, is

1. In a brush-holder fordynamos and motors, the combination withV a movable carriage mounted upon a suitable support and having a seat for the brush and risers at each side thereof, of a clamp plate located between said risers, and cam levers mounted. on a shaft journaled in said risers, whereby the brush may be held to the carriage, substantially as described.

2. In a brush holder for dynamos and motors, the combination with a movable carriage mounted in ways on a suitable support and provided with flanges and risers at each side, of a clamping plate located between the risers and provided with a recessed boss for the reception of the end of one of the conductors, springs secured to the clamping plate, and cam levers bearing against said springs, whereby the brush may be held yieldingly to its seat, substantially as described.

3. In a brush holder for dynamos and motors, the combination with the main frame having suitable longitudinal ways, of a movable carriage having Iianges fitted and adapted to move in said ways, a segment pivoted in bearings below said carriage and connected thereto bya strap connected to said segment and a spiral springl secured at one end to the pivotal shaft of the segment and at the other to the main frame o r support, so as to press the carriage forward toward the com mutator of the dynamo or motor when the device is in place, substantially as described.

4. In a brush holder for dynainos and m0- tors, the combination with a movable car-4 riage, of a segment secured to ashaft mounted in bearings inthe main frame below the carriage, a coiled spriug'secured` to the shaft and to the main frame, a ratchet wheel mounted upon the said shaft, and a pawl, whereby the tension of the spring may be regulated, substantially as described.

5. The combination of a support or frame. a carriage movable therein, a loose shaft mounted in the support, a coiledY spring connected with the loose shaft and the 'carriagemeaus for rotating the loose shaft to adjust the tension of the spring and means for locking the shaft in its adjusted position, substantially as described.

In testimony whereof I affix my signature in the presence of two witnesses.

JOHN R. COFFMAN.

Witnesses:

WM. M. STOCKBRIDGE, THEO. L. GATCHEL. 

